The prior art is replete with disclosures of lipstick cartridges of the repel/propel-type wherein a cam within the container drives the pomade up as it is turned with respect to the base. Containers of this type have been used with pomades that remained moist and readily transferable from the pomade stick to the lips, because the formulations have generally been waxy and have withstood continuous exposure to the air.
However, fashion trends call for formulations that exhibit low transfer characteristics after being applied to the lips. As a result, the pomade must contain greater amounts of pigment suspended in highly volatile carriers, such as silicon-based solvents. Because the solvents are volatile, continued exposure to the air results in rapid evaporation and drying out of the pomades so that they produce an unsatisfactory application to the lips. In addition, the pomades shrink and become loose in the container.
For the above reason, there has been a need for a lipstick container including means to seal the pomade from the surrounding air.
In attempting to develop a sealed lipstick, an approach has been to contain the base with a cup-like sleeve and provide the usual inverted cup-shaped cover which contains an inverted cup-shaped plastic sealing insert adapted to telescope over the top of the sleeve. To achieve good sealing, an inward rib has been added about the inside of the mouth of the insert. Such a rib has made effective line contact about the sleeve.
The effectiveness of the seal has actually defeated the integrity of the system described because, when it engages the sleeve, it is so effective that the remaining travel of the cover to the "home" position on the container has resulted in compression of air in the cover/container assembly. Subsequently, when the lipstick has been allowed to rest in the owner's handbag, for instance, the compressed air has forced the cover off the container, resulting in no protection at all against the drying of the pomade. Also, high environmental temperatures can result in excessive solvent evaporation within the sealed container causing a pressure rise that forces the cover off the container. The above-described ejection of the cover is the action with which the present invention deals.